Method for channel irreversibility correction and temporal/spatial separation of polarized beams, and multibeam antenna device using same

ABSTRACT

Disclosed are a method for temporal/spatial polarized beams and channel non-reciprocity correction and a multi-beam antenna apparatus using the same. According to one aspect of the present disclosure, a multi-beam antenna apparatus includes an array antenna including transmission antenna elements used for forming a plurality of transmission beams and reception antenna elements used for forming a plurality of reception beams. The multi-beam antenna apparatus separates polarized beams temporally and spatially by using two kinds of different orthogonal polarizations, while corrects a channel non-reciprocity which occurs due to temporal polarization separation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of International Application No.PCT/KR2021/015883, filed on Nov. 4, 2021, which claims priority toPatent Application No. 10-2020-0145879 filed in Korea on Nov. 4, 2020,and Patent Application No. 10-2021-0150406 filed in Korea on Nov. 4,2021, which are incorporated herein by reference in their entirety.

TECH/VICAL FIELD

The present disclosure relates to an antenna apparatus which may begenerally used in a cellular communication system, and moreparticularly, to a method for temporally and spatially separatingpolarized beams and correcting a channel non-reciprocity which occursdue to polarization separation, and an antenna apparatus using the same.

BACKGROUND

Contents described in this section merely provide background informationon the present disclosure and do not constitute the related art.

In order to meet a demand for wireless data traffic, which is on therise after commercialization of a 4th generation (4G) communicationsystem, efforts are being made to develop an improved 5G generationcommunication system or pre-5G communication system.

For this reason, the 5G communication system or the pre-5G communicationsystem is called a beyond 4G network communication system or a post longterm evolution (LTE) system.

In order to achieve a high data transmission rate, implementation of the5G communication system in an ultra-high frequency (mmWave) band (e.g.,60 GHz band) is considered. In order to alleviate a path loss of radiowaves in the ultra-high frequency band and to increase a transmissiondistance of the radio waves, in the 5G communication system,beamforming, massive multiple input and multiple output (MIMO), fulldimensional MIMO (FD-MIMO), array antenna, and large-scale antennatechnologies are being discussed.

In addition, in order to improve a network of the system, in the 5Gcommunication system, technological development of advanced small cell,cloud radio access network (RAN), ultra-dense network, Device to Devicecommunication (D2D), wireless backhaul, moving network, cooperativecommunication, Coordinated Multi-Points (CoMP), and receptioninterference cancellation are being made.

Besides, in the 5G system, Hybrid Frequency Shift Keying and QuadratureAmplitude Modulation (FQAM) and Sliding Window Superposition Coding(SWSC) which are advanced coding modulation (ACM) scheme, and FilterBank Multi Carrier (FBMC), Non Orthogonal Multiple Access (NOMA), andSparse Code Multiple Access (SCMA) which are advanced accesstechnologies are developed.

In order to overcome a problem of the path loss due to characteristicsof the ultra-high frequency band (e.g., mmWave), the 5G communicationsystem is operated to increase a signal gain by using a beamformingtechnique.

SUMMARY Technical Problem

An aspect of the present disclosure provides a method for temporally andspatially separating polarized beams by using two kinds of differentorthogonal polarizations, while correcting a channel non-reciprocitywhich occurs due to polarization separation and a multi-beam antennaapparatus using the same.

Technical Solution

An aspect of the present disclosure provides a method fortemporal/spatial polarized beams and channel non-reciprocity correctionand a multi-beam antenna apparatus using the same. According to oneaspect of the present disclosure, presented is a method performed by amulti-beam antenna apparatus. The multi-beam antenna apparatus comprisesan array antenna which includes transmission antenna elements used forforming a plurality of transmission beams and reception antenna elementsused for forming a plurality of reception beams.

The method includes generating a plurality of transmission polarizationcomponents from transmission signals corresponding to a pair oftransmission channels related to each transmission beam, and outputtinga pair of transmission polarization components corresponding to a firstorthogonal polarization or a pair of transmission polarizationcomponents corresponding to a second orthogonal polarization among theplurality of transmission polarization components with respect to a pairof transmission channels related to each transmission beam so thatspatially contiguous transmission beams have different orthogonalpolarizations.

In some embodiments, in order to correct a channel non-reciprocity, themethod further includes generating a plurality of reception polarizationcomponents from reception signals corresponding to a pair of receptionchannels related to each reception beam, and outputting a pair ofreception polarization components corresponding to orthogonalpolarizations of the transmission beam formed in the spatially samedirection among the plurality of reception polarization components withrespect to a pair of reception channels related to each reception beam.Alternatively, in order to correct a channel non-reciprocity, the methodfurther includes generating polarization-converted signals correspondingto an orthogonal polarization of a transmission beam formed in thespatially same direction as each reception beam from reception signalscorresponding to a pair of reception channels related to each receptionbeam.

An aspect of the present disclosure provides a multi-beam antennaapparatus using two kinds of orthogonal polarizations. The antennaapparatus comprises an array antenna including transmission antennaelements used for forming a plurality of transmission beams andreception antenna elements used for forming a plurality of receptionbeams. The antenna apparatus further comprises a transmissionpolarization composition unit for generating a plurality of transmissionpolarization components from transmission signals corresponding to apair of transmission channels related to each transmission beam. Theantenna apparatus further comprises a transmission polarizationallocation unit for outputting a pair of transmission polarizationcomponents corresponding to a first orthogonal polarization or a pair oftransmission polarization components corresponding to a secondorthogonal polarization among the plurality of transmission polarizationcomponents with respect to a pair of transmission channels related toeach transmission beam so that spatially contiguous transmission beamshave different orthogonal polarizations.

In some embodiments, the antenna apparatus further comprises a receptionpolarization composition unit for generating a plurality of receptionpolarization components from reception signals corresponding to a pairof reception channels related to each reception beam; and a receptionpolarization allocation unit for outputting a pair of receptionpolarization components corresponding to orthogonal polarizations of thetransmission beam formed in the spatially same direction among theplurality of reception polarization components with respect to a pair ofreception channels related to each reception beam. Alternatively, theantenna apparatus further comprises a polarization conversion unit forgenerating polarization-converted signals corresponding to an orthogonalpolarization of a transmission beam formed in the spatially samedirection as each reception beam from reception signals corresponding toa pair of reception channels related to each reception beam.

Advantageous Effects

As described above, by adopting an array antenna including transmissionantenna elements and reception antenna elements, the antenna apparatusaccording to the present disclosure does not require a switchingoperation which may worsen signal loss and a noise figure (NF) inimplementing time division duplexing (TDD).

In addition, since the antenna apparatus according to the presentdisclosure can separate multi-beams in various orientations in a space,the antenna apparatus can extend cell coverage, and reduce a correlationbetween beams through polarization separation (i.e., spatialpolarization separation) of the multi-beams, thereby further enhancing acommunication quality.

Furthermore, the antenna apparatus according to the present disclosureperforms polarization conversion for reception signals received from thereception antenna element or performs polarization composition andpolarization allocation to correct the channel non-reciprocity betweenan uplink channel and a downlink channel which occurs due to spatial andtemporal polarization separation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view for describing an NF deterioration problemwhich occurs in a conventional antenna apparatus.

FIG. 2A to FIG. 2D each is a block diagram schematically illustrating anexemplary configuration of an antenna apparatus capable of implementingtechnologies of the present disclosure.

FIG. 3A to FIG. 3D are diagrams for describing various examples for anantenna module which may be adopted in an antenna system of the presentdisclosure.

FIG. 4 is a conceptual view for describing polarization composition andpolarization allocation performed in relation to one transmissionantenna element according to an embodiment of the present disclosure.

FIG. 5 is a conceptual view for describing polarization composition andpolarization allocation performed in relation to one reception antennaelement according to an embodiment of the present disclosure.

FIG. 6 is a block diagram illustrating an exemplary structure forperforming polarization composition and polarization allocation fortransmission signals in the antenna apparatus according to an embodimentof the present disclosure.

FIG. 7 is a conceptual view for describing spatial polarizationseparation in a horizontal direction and a vertical direction providedby the antenna apparatus according to an embodiment of the presentdisclosure.

FIG. 8 is a conceptual view for describing temporal polarizationseparation provided by the antenna apparatus according to an embodimentof the present disclosure.

FIG. 9 is a conceptual view for describing a channel non-reciprocityproblem which may occur when different dual polarized waves are usedbetween transmission of a signal and reception of the signal.

FIG. 10A and FIG. 10B are conceptual views for describing a method forcorrecting a channel non-reciprocity by using polarization conversionaccording to an embodiment of the present disclosure.

FIG. 11A and FIG. 11B are conceptual views for describing a method forcorrecting a channel non-reciprocity by using polarization compositionand polarization allocation according to an embodiment of the presentdisclosure.

FIG. 12 is a block diagram illustrating an exemplary structure forperforming transmission polarization composition calibration in theantenna apparatus according to an embodiment of the present disclosure.

FIG. 13 is a flowchart illustrating a method performed by a multi-beamantenna apparatus using quadruple polarization according to anembodiment of the present disclosure.

[Explanation of Reference Numerals] 10: Multi-beam antenna apparatus110: Digital processing unit 120: RF processing unit 130: Array antenna1310: Antenna module 1312: Transmission antenna element 1314: Receptionantenna element

DETAILED DESCRIPTION

Hereinafter, some embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. Itshould be noted that, in adding reference numerals to the constituentelements in the respective drawings, like reference numerals designatelike elements, although the elements are shown in different drawings.Further, in the following description of the present disclosure, adetailed description of known functions and configurations incorporatedherein will be omitted to avoid obscuring the subject matter of thepresent disclosure.

Additionally, various terms such as first, second, A, B, (a), (b), etc.,are used solely to differentiate one component from the other but not toimply or suggest the substances, order, or sequence of the components.Throughout this specification, when a part ‘includes’ or ‘comprises’ acomponent, the part is meant to further include other components, not toexclude thereof unless specifically stated to the contrary. The termssuch as ‘unit’, ‘module’, and the like refer to one or more units forprocessing at least one function or operation, which may be implementedby hardware, software, or a combination thereof.

FIG. 1 is a conceptual view for describing an NF deterioration problemwhich occurs in a conventional antenna apparatus.

A conventional antenna apparatus which operates in a TDD schemeillustrated in FIG. 1 may be configured to include an antenna ANT, afilter, a switch S/W, a PA, an LNA, an AD converter (not shown), and adigital signal processor (not shown) (which may be implemented in FPGA).

The antenna ANT may have a form in which a plurality of antenna modulesare arrayed, and each antenna module may be a dual polarized antennamodule constituted by two radiators having a geometric orientation whichare vertical to each other (i.e., having polarization characteristicsorthogonal to each other). The antenna modules perform a signaltransmission function when the switch S/W is connected to a transmission(Tx) line, and perform a signal reception function when the switch S/Wis connected to a reception (Rx) line. Accordingly, the antennaapparatus of FIG. 1 implements a TDD function by a selective switchingoperation of the switch S/W.

Signal loss may occur in a transmission signal or a reception signal dueto the switching operation, and the signal loss may also occur evenwhile the reception signal is delivered to a rear end of the apparatusthrough a RF cable. The signal loss may cause problems of deterioratinga noise figure (NF), and limiting uplink coverage extension of awireless communication system.

The multi-beam antenna apparatus according to the present disclosureadopts an array antenna constituted by antenna modules having a pair ofdual polarized antenna elements to use one dual polarized antennaelement for transmitting a radio signal and use the other one dualpolarized antenna element for receiving the radio signal. Accordingly,the multi-beam antenna apparatus does not require the switchingoperation which may deteriorate the signal loss and the noise figure inimplementing TDD.

Further, the multi-beam antenna apparatus according to the presentdisclosure allocates two kinds of orthogonal polarized waves totransmission channels so that spatially contiguous transmission beamshave different orthogonal polarizations to spatially separate two kindsof orthogonal polarizations.

FIGS. 2A to 2D are block diagrams schematically illustrating anexemplary configuration of a multi-beam antenna apparatus capable ofimplementing technologies of the present disclosure.

The multi-beam antenna apparatus 10 may be an M x N multi-inputmulti-output (MIMO) antenna. Therefore, the antenna apparatus 10 mayhave M transmission channels and M reception channels. The antennaapparatus 10 may include a digital processing unit 110, an RF processingunit 120, and an antenna array 130.

As illustrated in FIGS. 2A and 2B, the digital processing unit 110 maybe configured to include a fronthaul interface 1110, a multi-beamforming unit 1120, a polarization composition unit 1130, a polarizationallocation unit 1140, an amplitude-phase calibration unit 1150, and apolarization conversion unit 1160. Alternatively, as illustrated inFIGS. 2C and 2D, the digital processing unit 110 may be configured to apolarization composition unit 1170 and a polarization allocation unit1180 instead of the polarization conversion unit 1160.

The RF processing unit 120 may be configured to include a plurality oftransmission radio frequency (RF) chains 1210, 1210-1 to 1210-M, and aplurality of reception RF chains 1220, 1220-1 to 1220-M.

A configuration of the antenna apparatus 10 in FIGS. 2A to 2D should beappreciated as being an exemplary configuration drawn for the purpose ofclarity. In another embodiment, any other appropriate components of theantenna apparatus 10 may be further used. Respective components of theantenna apparatus 10 may be generally implemented by using dedicatedhardware, for example, by using one or more application-specificintegrated circuits (ASIC), radio frequency integrated circuits (RFIC),and/or field programmable gate arrays (FPGA). Alternatively, somecomponents may be implemented by using software executed in programmablehardware or by using a combination of hardware and software.

The array antenna 130 may include a plurality of array elements orantenna elements arranged in a plurality of rows and a plurality ofcolumns. In some embodiments, each array element may be a dual polarizedantenna element having dual polarization characteristics. Each of theplurality of array elements may be divided into a transmission antennaelement and a reception antenna element. The transmission antennaelement may be used for transmission of signal and the reception antennaelement may be used for reception of the signal. Orthogonal polarizationcharacteristics of the transmission antenna element and the orthogonalpolarization characteristics of the reception antenna element may be thesame as each other and also different from each other. In some otherembodiments, each array element may also be a quadruple polarizedantenna element having quadruple polarization characteristics. Thepolarization characteristics and the structure of the array element willbe described below with reference to FIGS. 3A to 3D.

The antenna apparatus 10 may implement a polarization diversity by usingthe orthogonal polarization characteristics provided by the arrayantenna 130. The antenna apparatus 10 may allocate dual orthogonalpolarizations to two transmission channels (or transmission signals)related to each transmission beam. The orthogonal polarization allocatedto the transmission channels may also be the same as or different fromthe dual orthogonal polarization characteristics of the transmissionantenna element included in the array antenna 130.

The antenna apparatus 10 may generate a transmission beam having adifferent orthogonal polarization from the orthogonal polarizationcharacteristics of the transmission antenna element through polarizationcomposition, and form a reception beam corresponding to an orthogonalpolarization different from the orthogonal polarization characteristicsof the reception antenna element through the polarization composition(that is, generate a signal component corresponding to the orthogonalpolarization different from the orthogonal polarization characteristicsof the reception antenna element).

The antenna apparatus 10 allocates two kinds of orthogonal polarizationsto the transmission channels so that spatially adjacent beams havedifferent orthogonal polarizations to spatially separate two kinds oforthogonal polarizations.

In the following description, two kinds of orthogonal polarizations arean orthogonal polarization constituted by ±45° linear polarized wavesand an orthogonal polarization constituted by vertical/horizontal (V/H)linear polarized waves, but the technologies of the present disclosureare also applicable to a combination of the orthogonal linear polarizedwaves and an orthogonal circular polarized wave constituted by leftcircular/right circular polarized waves.

In the following description, the polarization composition unit 1130 andthe polarization allocation unit 1140 positioned in a transmission pathmay be referred to as a transmission polarization composition unit 1130and a transmission polarization allocation unit 1140, respectively, andthe polarization composition unit 1170 and the polarization allocationunit 1180 positioned in a reception path may also be referred to as areception polarization composition unit 1170 and a receptionpolarization allocation unit 1180, respectively.

Transmission Signal Processing

Transmission signals of M transmission channels may be radiated throughthe array antenna 130 via transmission paths constituted by themulti-beam forming unit 1120, the polarization composition unit 1130,the polarization allocation unit 1140, the amplitude-phase calibrationunit 1150, and the transmission RF chains 1210-1 to 1210-M in a beamform. Each of the transmission channels has a corresponding transmissionpath. Here, the transmission signal may also be referred to as adownlink signal. The transmission path refers to a path through whichthe transmission signal proceeds in the antenna apparatus 10. Therefore,the transmission path may also be referred to as “path through which thetransmission signal proceeds” or “path in which the transmission signalis processed”.

First, the transmission signals input through the fronthaul interface1110 are input into the polarization composition unit 1130 to go througha polarization composition process. The polarization composition unit1130 may compose four polarization components for each of a pair oftransmission signals to be radiated through a transmission antennaelement to be described below, and output the polarization components tothe polarization allocation unit 1140. The polarization componentsoutput from the polarization composition unit 1130 may also be referredto as “polarized signals”. It is important that the polarizationcomponents composed by the polarization composition unit 1130 are fed tothe array antenna 130 via subsequent components and radiated to a freespace, and as a result, substantial polarization composition is made.

The polarization allocation unit 1140 may determine orthogonalpolarizations to be allocated to two transmission channels (or twotransmission signals) related to each transmission beam so that thespatially adjacent transmission beams have different orthogonalpolarizations. The polarization allocation unit 1140 may output some offour polarization components composed by the polarization compositionunit 1130 to two transmission paths to correspond to the determinedorthogonal polarizations. The polarization components output to eachtransmission path may also be referred to as “polarization components(polarized signals) of the transmission signal”, “polarizationcomponents (polarized signals) of the transmission channel”, or“transmission polarization components (transmission polarized signals)”.The orthogonal polarization of the transmission beam may be determinedaccording to orthogonal polarization characteristics of the polarizationcomponents and the transmission antenna element output from thepolarization allocation unit 1140. Polarization composition which occursin the transmission antenna element according to polarizationcomposition and polarization allocation will be described below withreference to FIG. 4 .

In order to compensate for variations of amplitude and phasecharacteristics between the transmission RF chains 1210-1 to 1210-M, thepolarization components of the respective transmission signals are inputinto the amplitude-phase calibration unit 1150 prior to reaching thetransmission RF chains 1210-1 to 1210-M. The amplitude and phasecharacteristics of the RF transmission path are related to an amplitudechange and a phase change which appear as an RF signal moves along an RFtransmission path provided by a transmission RF chain.

The amplitude-phase calibration unit 1150 performs a function ofcompensating for the variations of the amplitude and phasecharacteristics between the transmission RF chains 1210-1 to 1210-M.Since the variation of the amplitude characteristic influencesbeamforming is slight, it is common to calibrate only a phase equallyfor all paths. However, since accuracy of the polarized wave compositionwhich occurs in the antenna array 130 according to the presentdisclosure significantly depends on amplitudes and phases of composedradio signals, the calibration of the amplitude and the phase increasesthe accuracy of the polarization composition.

The polarization components of the transmission signal which goesthrough the amplitude-phase calibration process may be converted into ananalog signal and subjected to RF signal processing by the transmissionRF chain 1210. The transmission RF chain 1210 may be configured toinclude a digital to analog converter (DAC), a filter, a mixer forfrequency up-conversion, and a power amplifier (PA).

The transmission signal RF signal-processed and converted into theanalog signal by the transmission RF chain 1210 may be radiated throughthe array antenna 130 in the beam form.

The multi-beam forming unit 1120 may precode the transmission signals sothat multi-beams are formed by the array antenna 130. A location of themulti-beam forming unit 1120 on the transmission path of the antennaapparatus 10 may vary depending on whether a weight vector (or precodingmatrix) is used in a baseband or whether the weight vector is used in anRF band.

First, as in an example of FIG. 2A or 2C, the multi-beam forming unit1122 may be positioned preceding the transmission polarizationcomposition unit 1130 in the transmission path of the signal. Themulti-beam forming unit 1122 performs digital beamforming. In this case,the weight vector or the precoding matrix is applied to (baseband)digital transmission signals by the multi-beam forming unit 1122, whichmay be converted into a plurality of precoded signals.

The digital transmission signal may be branched into a plurality ofsignals having phases and amplitudes different according to the appliedweight vector. Further, the branched signals are reinforced andinterfered in a specific angle or orientation (an orientation in whichcommunication resources are concentrated) through the array antenna 130to be radiated in the beam form. Therefore, an orientation and a shapeof the beam may be determined according to a value of the weight vectorapplied to the digital transmission signal.

Next, as in an example of FIG. 2B or 2D, the multi-beam forming unit1124 may be positioned after the transmission RF chain 1210 in atransmission process of the signal. Therefore, the multi-beam formingunit 1124 may perform analog beamforming. In this case, the multi-beamforming unit 1124 may branch the analog signal received from eachtransmission RF chain 1210 into multiple paths, and control phases andamplitudes of the respective branched signals. The beam forming unit1124 may be configured to include multiple phase shifters controllingthe phases of the respective branched signals and multiple poweramplifiers controlling the amplitudes of the respective branchedsignals. That is, the phase shifter and the power amplifier process theweight vector in an analog domain. The analog signals of which phasesand amplitudes are controlled are reinforced and interfered in aspecific angle or direction through the array antenna 130 to be radiatedin the beam form. Here, a function of the transmission RF chain 1210 mayalso be performed by the multi-beam forming unit 1224 substantiallyconstituted by analog components, so the transmission RF chain 1210 mayalso be removed from the antenna apparatus 10.

Reception Signal Processing

Reception signals (or uplink signals) corresponding to M receptionchannels may be received through the array antenna 130, and thenprocessed through the reception paths constituted by the reception RFchain 1220, the amplitude-phase calibration unit 1150, the polarizationconversion unit 1160 (alternatively, the reception polarizationcomposition unit 1170 and the reception polarization allocation unit1180), and the multi-beam forming unit 1120. The respective receptionchannels have corresponding reception paths. Here, the reception signalmay also be referred to as uplink signal. The reception path refers apath in which the reception signal proceeds in the antenna apparatus 10.Therefore, the reception path may also be referred to as “path throughwhich the reception signal proceeds” or “path in which the receptionsignal is processed”.

The analog reception signals received through the array antenna 130 maybe subjected to Rf-signal processing by corresponding reception RFchains 1220-1 to 1220-M. Each reception RF chain 1220 may be configuredto include an analog to digital converter (ADC), a mixer for frequencydown-conversion, and a low noise amplifier (LNA).

The reception signal converted into the digital signal via the receptionRF chain 1220 may go through a process of calibrating the variations ofthe amplitude and phase characteristics between the reception RF chains1220-1 to 1220-M by the amplitude-phase calibration unit 1150.

With respect to the transmission beam and the reception beam formed inthe same spatial direction, the orthogonal polarization (changed byorthogonal polarization allocation of the transmission polarizationallocation unit 1140) may also be the same as or different from theorthogonal polarization of the reception signal (defined by theorthogonal polarization characteristics of the reception antennaelement). As described below, when the orthogonal polarization isdifferent from the orthogonal polarization of the reception signal,radio channel characteristics are different between the uplink and thedownlink, and as a result, a downlink/uplink channel reciprocity is notestablished.

As illustrated in FIGS. 2A and 2B, the antenna apparatus 10 may includethe polarization conversion unit 1160 correcting the channelnon-reciprocity by using the polarization conversion. The polarizationconversion unit 1160 performs the polarization conversion for thereception signals output from the amplitude-phase calibration unit 1150to output polarization-converted signals having the same orthogonalpolarization as the orthogonal polarization of the transmission beam.

For example, when the transmission beam has a ±45° orthogonalpolarization and the reception antenna element has the V/H orthogonalpolarization characteristics, the polarization conversion unit 1160performs polarization conversion for the reception signals of the V/Hpolarization to output polarization converted signals having the sameorthogonal polarization)(±45° as the orthogonal polarization of thetransmission beam. As another example, when the transmission beam hasthe V/H orthogonal polarization and the reception antenna element hasthe V/H orthogonal polarization characteristics, the orthogonalpolarization of the transmission beam and the orthogonal polarization ofthe reception signal are the same as each other, so the polarizationconversion unit 1160 may not perform the polarization conversion for thereception signals.

Alternatively, as illustrated in FIGS. 2C and 2D, the antenna apparatus10 may include the polarization composition unit 1170 and thepolarization allocation unit 1180 that correct the channelnon-reciprocity by using the polarization composition and thepolarization allocation.

The polarization composition unit 1170 may compose four polarizationcomponents for each of a pair of reception signals received through eachreception antenna element, and output the polarization components to thepolarization allocation unit 1180. The polarization components outputfrom the polarization composition unit 1170 may also be referred to as“polarized signals”.

The polarization allocation unit 1180 may determine orthogonalpolarizations to be allocated to two reception channels (or tworeception signals) related to each reception antenna element. Thepolarization allocation unit 1180 may allocate the same orthogonalpolarization as the orthogonal polarization (or the orthogonalpolarization of the transmission beam) set in two correspondingtransmission channels to two reception channels.

The polarization allocation unit 1180 may output two polarizationcomponents to be transmitted to a digital unit (DU) through thefronthaul interface 1110 among four polarization components composed bythe polarization composition unit 1170 to correspond to the determinedorthogonal polarizations. The polarization components allocated to eachreception channel may be referred to as “polarization components(polarized signals) of the reception channel” or “polarizationcomponents (polarized signals) of the reception channel” or “receptionpolarization components (reception polarized signals)”.

For example, when the ±45° orthogonal polarizations are set in twotransmission channels (therefore, the transmission beam has the ±45°orthogonal polarization), and the reception antenna element has the V/Horthogonal polarization characteristics, the polarization allocationunit 1180 may output two polarization components corresponding to the±45° orthogonal polarizations among four polarization componentscomposed by the polarization composition unit 1170. As another example,when the V/H orthogonal polarizations are set in two transmissionchannels (therefore, the transmission beam has the V/H orthogonalpolarization), and the reception antenna element has the V/H orthogonalpolarization characteristics, the polarization allocation unit 1180 mayoutput two polarization components corresponding to the V/H orthogonalpolarizations among four polarization components composed by thepolarization composition unit 1170.

A detailed description of the channel non-reciprocity, and an operationof the polarization conversion unit 1160 for calibrating the channelnon-reciprocity, and operations of the polarization composition unit1170 and the polarization allocation unit 1180 will be made below withreference to FIGS. 9 , FIG. 10A, FIG. 10B, FIG. 11A and FIG. 11B.

The reception signals may include a plurality of signals havingdifferent phases and amplitudes, which correspond to the relatedreception antenna elements. The multi-beam forming unit 1120 adjusts thephases and amplitudes of the plurality of signals, and then aggregatesthe adjusted signals to generate or reconstruct the reception signal.This process may be appreciated as an opposite process to a process inwhich the multi-beam forming unit 1120 forms the plurality of signalshaving different phases and amplitudes from the transmission signal. Tothis end, as illustrated in FIGS. 2A and 2C, the multi-beam forming unit1122 is positioned after the polarization composition unit 1160 and thereception polarization allocation unit 1180 in the reception path toperform the digital beamforming, or as illustrated in FIGS. 2B and 2D,the multi-beam forming unit 1122 is positioned between the array antenna130 and the reception RF chain 1220 in the reception path to perform theanalog beamforming. In FIG. 2B, a function of the reception RF chain1220 may also be performed by the multi-beam forming unit 1224substantially constituted by analog components, so the reception RFchain 1210 may also be removed from the antenna apparatus 10.

DU and RU

Meanwhile, in a so-called “stand-alone base station”, signal processingfunctions corresponding to the digital unit (DU) and a radio unit (RU),respectively are included in one physical system, and one physicalsystem is installed in a service target area. Contrary to this,according to a cloud radio access network (C-RAN) architecture, the DUand the RU are physically separated, and only the RU is installed in theservice target area, and a BBU pool which is centralized DUs has acontrol management function for a plurality of RUs forming eachindependent cell.

The DU as a part which takes charge of digital signal processing andresource management control functions is connected to a core networkthrough backhaul. The RU as a part which takes charge of a radio signalprocessing function converts the digital signal received from the DUinto a radio frequency signal according to a frequency band, andamplifies the radio frequency signal, and converts the RF signalreceived by the antenna into the digital signal, and transmits thedigital signal to the DU.

The antenna apparatus 10 may be installed in the stand-alone basestation in which the DU and the RU are included in one physical system,or also installed in the RU in a C-RAN structure in which the DU and theRU are physically separated. Hereinafter, an example in which theantenna apparatus 10 is installed in the RU in the C-RAN structure willbe primarily described.

The baseband signal may be a signal which goes through basebandprocessing such as a scrambling process, a modulation process, and alayer mapping process. The scrambling process corresponds to a processof encrypting the baseband signal by using a scramble signal in order todistinguish a base station or a terminal. The modulation processcorresponds to a process of modulating scrambled signals into aplurality of modulation symbols. The scrambled signal is input into amodulation mapper (not illustrated) to be modulated through a binaryphase shift keying (BPSK), quadrature phase shift keying (QPSK), or16QAM/64QAM (quadrature amplitude modulation) scheme. The layer mappingprocess corresponds to a process of mapping the modulation symbols toone or more transmission layers in order to separate the signals foreach antenna. With respect to the modulation symbols obtained throughthe modulation process, a process of mapping the modulation symbols toresource elements may be further performed.

When the antenna apparatus 10 is installed in the RU in the C-RANstructure, the above processes may be performed by the centralized DU.On the contrary, when the antenna apparatus 10 is installed in thestand-alone base station, the above processes may be performed by the DUin the base station.

Exchange of signals or data between the DU and the RU is made throughthe fronthaul or a fronthaul link. The fronthaul link is a linkconnecting the DU and the RU in a cellular radio access network. Thefronthaul interface 1110 of the antenna apparatus 10 may be implementedto conform to standards such as Common Public Radio Interface (CPRI),enhanced CPRI (eCPRI), Open Radio Equipment Interface (ORI), Open BaseStation Architecture Initiative (OBSAI), etc.

When the antenna apparatus 10 of the present disclosure is implementedin the RU, the antenna apparatus 10 may be divided into the digitalprocessing unit 110, the RF processing unit 120, and the array antenna130.

The RF processing unit 120 takes charge of analog signal processing forthe transmission signals and the reception signals. The RF processingunit 120 may be configured to include the RF chains 1210 and 1220 asillustrated in FIG. 2A, or configured to include the RF chains 1210 and1220, and the multi-beam forming unit 1124 as illustrated in FIG. 2B.

The digital processing unit 110 takes charge of the digital signalprocessing for the transmission signals and the reception signals. Thedigital processing unit 110 may be implemented as a digital front end(DFE). The DFE means replacing the existing analog function blocks witha digital signal processing (DSP) block. When the digital processingunit 110 is implemented as the DFE, a design consumption time, powerconsumption, and an area may be reduced, and a flexibility capable ofmultiple modes and multiple bands may be secured.

The digital processing unit 110 may further perform an inverse fastFourier transform (IFFT) operation and an FFT operation for thepolarization-converted signals. Further, the digital processing unit 110may insert a guard interval in order to prevent inter-symbolinterference (ISI). To this end, the digital processing unit 110 may beconfigured to further include an IFFT unit (not illustrated)/FFT unit(not illustrated), and a cyclic prefix (CP) (not illustrated).

Antenna Elements of Array Antenna

FIGS. 3A to 3D are diagrams for describing various structures andorthogonal polarization characteristics of the antenna module 1310 whichmay be adopted in the array antenna 130 of the antenna system of thepresent disclosure.

As illustrated in FIGS. 3A to 3D, the antenna module 1310 may beconstituted by a pair of a transmission antenna element 1312corresponding to a transmitting antenna and a reception antenna element1314 corresponding to a receiving antenna. The transmission antennaelement 1312 is connected to transmission lines Tx1 and Tx2 to be usedfor transmitting the signal, and the reception antenna element 1314 isconnected to reception lines Rx1 and Rx2 to be used for receiving thesignal.

The transmission antenna element 1312 is a dual polarized antennaelement including two radiators having polarization characteristicsorthogonal to each other, and the reception antenna element 1314 is alsoa dual polarized antenna element including two radiators havingpolarization characteristics orthogonal to each other.

The orthogonal polarization characteristics of the transmission antennaelement 1312 and the orthogonal polarization characteristics of thereception antenna element 1314 may be different (for example, see (b)and (c) of FIG. 3A). For example, the radiators included in thetransmission antenna element 1312 may have +45° and −45° polarizationcharacteristics, respectively, and the radiators included in thereception antenna element 1314 may have the V and H polarizationcharacteristics, respectively. As another example, the radiatorsincluded in the transmission antenna element 1312 may have the V and Hpolarization characteristics, respectively, and the radiators includedin the reception antenna element 1314 may have the +45° and −45°polarization characteristics, respectively. That is, the antenna module1310 may provide two kinds of orthogonal polarization characteristicsincluding dual orthogonal polarizations of the transmission antennaelement 1312 and dual orthogonal polarizations of the reception antennaelement 1314.

The orthogonal polarization characteristics of the transmission antennaelement 1312 and the orthogonal polarization characteristics of thereception antenna element 1314 may also be the same as each other (forexample, see (a) and (d) of FIG. 3A). In the embodiment in which theantenna module 1310 is adopted, as described below with reference toFIG. 4 , a beam radiated from the transmission antenna element 1312 mayhave a different dual orthogonal polarization orientation from the dualpolarization characteristics of the transmission antenna element 1312 byrelying on polarization components of transmitted signals to bedelivered through the transmission lines Tx1 and Tx2. Therefore, evenwhen the antenna module 1310 illustrated in (a) and (d) of FIG. 3A, theantenna apparatus 10 may use different dual orthogonal polarizationsbetween the transmission beam and the reception beam.

In the antenna module 1310 illustrated in FIG. 3A, two radiatorsconstituting the transmission antenna element 1312 are arranged to crosseach other at a first intersection, and the radiators constituting thereception antenna element 1314 are arranged to cross each other at asecond intersection. As a distance between the first intersection andthe second intersection decreases, the efficiency of an area occupied bythe antenna module 1310 increases.

Referring to FIG. 3B, a pair of radiators constituting the receptionantenna element 1314 may be (i) disposed adjacent to a left side and anupper side of the transmission antenna element 1312 (see (a) of FIG.3B), (ii) disposed adjacent to the left side and a lower side of thetransmission antenna element 1312 (see (b) of FIG. 3B), (iii) disposedadjacent to the right side and the upper side of the transmissionantenna element 1312 (see (c) of FIG. 3B), or (iv) disposed adjacent tothe right side and the lower side of the transmission antenna element1312 (see (d) of FIG. 3B).

Referring to FIG. 3C, a pair of radiators constituting the transmissionantenna element 1312 may be (i) disposed adjacent to a top left side anda bottom left side of the reception antenna element 1314 (see (a) ofFIG. 3C), (ii) disposed adjacent to the bottom left side and a bottomright side of the reception antenna element 1314 (see (b) of FIG. 3C),(iii) disposed adjacent to the top left side and a top right side of thereception antenna element 1314 (see (c) of FIG. 3C), or (iv) disposedadjacent to the top right side and the bottom right side of thereception antenna element 1314 (see (d) of FIG. 3C).

As such, any one antenna element 1312 or 1314 is disposed adjacent to aside surface of the other one antenna element 1314 or 1312, the antennamodule 1310 illustrated in FIGS. 3B and 3C may provide more enhancedarea efficiency than the antenna module 1310. Further, the enhancementof the area efficiency may lead to convenience of manufacturing,installation, maintenance, etc.

In the antenna module 1310 illustrated in FIG. 3D, two radiatorsconstituting the transmission antenna element 1312 and the radiatorsconstituting the reception antenna element 1314 cross each other at oneintersection 1316, and therefore, the area efficiency of an array ofFIG. 3D is maximized as compared with arrays of FIG. 3A to FIG. 3C.

Moreover, in the above description described with reference to FIG. 3Ato FIG. 3D, it should be appreciated that a location of the transmissionantenna element 1312 and a location of the reception antenna element1314 may be reversed.

Polarization Composition and Polarization Allocation

FIG. 4 is a conceptual view for describing polarization composition andpolarization allocation performed in relation to one transmissionantenna element according to an embodiment of the present disclosure,and FIG. 5 is a conceptual view for describing polarization compositionand polarization allocation performed in relation to one receptionantenna element according to an embodiment of the present disclosure.

As described above, the transmission polarization composition unit 1130may compose and output four different polarization components from twotransmission signals to be transmitted through one transmission antennaelement 1312.

Referring to FIG. 4 , the transmission polarization composition unit1130 may compose and output different polarization components “S1”,“S2”, “S1+S2”, and “S1+S2e^(iπ)” from transmission signals 51 and S2.Here, “S1” and “S2” are used for generating beams having the samepolarization orientation as the polarization characteristics of thetransmission antenna element 1312, and “S1+S2” and “S1+S2e^(iπ)” areused for generating beams having different polarization orientationsfrom the polarization characteristics of the transmission antennaelement 1312.

The composition of the polarization components performed by thetransmission polarization composition unit 1130 may be implementedthrough a matrix operation of Equation 1 below.

$\begin{matrix}{{\begin{bmatrix}1 & 0 \\0 & 1 \\1 & 1 \\1 & e^{j\pi}\end{bmatrix}\begin{bmatrix}S_{1} \\S_{2}\end{bmatrix}} = \begin{bmatrix}S_{1} \\S_{2} \\{S_{1} + S_{2}} \\{S_{1} + {S_{2}e^{j\pi}}}\end{bmatrix}} & \left\lbrack {{Equation}1} \right\rbrack\end{matrix}$

In Equation 1 above,

$\begin{bmatrix}1 & 0 \\0 & 1 \\1 & 1 \\1 & e^{j\pi}\end{bmatrix}$

represents a polarization vector composition-decomposition (PVCD)matrix. Here, in order to prevent powers of third and fourthpolarization components “S1+S2” and “S1+S2e^(iπ)”, a scale coefficientmay be applied to elements in a third row and elements in a fourth row.The scale coefficient may be 1/√2.

The transmission polarization allocation unit 1140 may output twopolarization components to be radiated through two radiators of thetransmission antenna element 1312 among four polarization components ofthe transmission signals S1 and S2 output from the transmissionpolarization composition unit 1130 to two transmission paths.

For example, the transmission polarization allocation unit 1140 may (i)output “S1” and “S2” (see (a) of FIG. 4 ) or (ii) output “S1+S2” and“S1+S2e^(iπ)” (see (b) of FIG. 4 ) among four polarization components“S1”, “S2”, “S1+S2”, and “S1+S2e^(iπ)”.

According to the polarization components output from the transmissionpolarization allocation unit 1140, beams radiated from the transmissionantenna element 1312 having the ±45° orthogonal polarizationcharacteristics may have the ±45° orthogonal polarization or the V/Horthogonal polarization.

As in (a) of FIG. 4 , when the polarization components “S1” and “S2” areallocated to the transmission channels, the polarization component “S1”radiated through the radiator having the +45° polarizationcharacteristics forms a beam pattern having +45° polarization and thepolarization component “S1” radiated through the radiator having the−45° polarization characteristics forms a beam pattern having −45°polarization. That is, the transmission antenna element 1312 having the±45° orthogonal polarization characteristics forms a beam pattern havingthe ±45° orthogonal polarization.

As in (b) of FIG. 4 , when the polarization components “S1+S2” and“S1+S2e^(iπ)” are allocated to the transmission channels, a polarizationcomposition occurs between the beam formed by the polarization component“S1+S2” radiated through the radiator having the +45° polarizationcharacteristics and the beam formed by the polarization component“S1+S2e^(iπ)” radiated through the radiator having the −45° polarizationcharacteristics.

Specifically, in the case of the polarization component “S1”, a firstbeam radiated through the radiator having the +45° polarizationcharacteristics has a +45° polarization orientation and a second beamradiated through the radiator having the −45° polarizationcharacteristics has a −45° polarization orientation, and as a result,the first beam and the second beam are composed, so a composition beamhaving a V polarization orientation appears. In the case of thepolarization component “S2”, a third beam radiated through the radiatorhaving the +45° polarization characteristics has the +45° polarizationorientation and a fourth beam radiated through the radiator having the−45° polarization characteristics has a “−45°+n” polarizationorientation, and as a result, the third beam and the fourth beam arecomposed, so a composition beam having the V polarization orientationappears.

Meanwhile, when the reception antenna element 1314 receives the radiosignals S1 and S2 in the free space, orthogonal polarizationorientations of reception signals a and b are determined by theorthogonal polarization characteristics of the reception antenna element1314. For example, when the dual polarization characteristics of thereception antenna element 1314 are the V/H orthogonal polarization, thereception signals have the V/H orthogonal polarization.

Referring to FIG. 5 , with respect to the radio signals S1 and S2, thereception signal a captured by the radiator having the V polarization ofthe reception antenna element 1314 includes an S1 signal component S1(V)of the V polarization and an S2 signal component S2(V) of the Vpolarization, and the reception signal b captured by the radiator havingthe H polarization includes an S1 signal component S1(H) of the Hpolarization and an S2 signal component S2(H) of the H polarization.

As described above, the reception polarization composition unit 1170 maycompose and output four different polarization components from tworeception signals a and b by received by one reception antenna element1314. The composition of the polarization components performed by thereception polarization composition unit 1170 may be implemented throughthe matrix operation of Equation 1.

As illustrated in FIG. 5 , the reception polarization composition unit1170 may compose and output different polarization components “a”, “b”,“a+b”, and “a+be^(iπ)” from the reception signals a and b for the RFsignals S1 and S2. Here, “a” and “b” are polarization components havingthe same polarization orientation as the polarization characteristics ofthe reception antenna element 1314, and “a+b” and “a+be^(iπ)” arepolarization components having different polarization orientations fromthe polarization characteristics of the reception antenna element 1314.

Specifically, the polarization component “a” has the S1 signal componentS1(V) of the V polarization and the S2 signal component S2(V) of the Vpolarization, and the polarization component “b” has the S1 signalcomponent S1(H) of the H polarization and the S2 signal component S2(H)of the H polarization.

Further, the polarization component “a+b” has (i) a +45°-polarization S1signal component S1(+45°) in which the S1 signal component S1(V) of theV polarization and the S1 signal component S1(H) of the H polarizationare composed and (ii) a +45°-polarization S2 signal component S2(+45°)in which the S2 signal component S2(V) of the V polarization and the S2signal component S2(H) of the H polarization are composed.

Further, the polarization component “a+be^(iπ)” has (i) a−45°-polarization S1 signal component S1(−45° in which the S1 signalcomponent S1(V) of the V polarization and the S1 signal componentS1(H+π) of H+π polarization are composed and (ii) a −45°-polarization S2signal component S2(−45° in which the S2 signal component S2(V) of the Vpolarization and the S2 signal component S2(H+π) of the H+π polarizationare composed.

The reception polarization allocation unit 1180 may output twopolarization components among the polarization components of thereception signals a and b output from the reception polarizationcomposition unit 1170 to two reception paths. For example, thetransmission polarization allocation unit 1180 may (i) output “a” and“b” (see (a) of FIG. 5 ) or (ii) output “a+b” and “a+be^(iπ)” (see (b)of FIG. 5 ) among four polarization components “a”, “b”, “a+b”, and“a+be^(iπ)”.

As in (a) of FIG. 5 , when the polarization components “a” and “b” areallocated to the reception channels, the signal components “S1(V) andS2(V)” and “S1(H) and S2(H)” of the same orthogonal polarization as theorthogonal polarization characteristics of the reception antenna element1314 are output to the reception channels, with respect to the RFsignals S1 and S1.

As in (b) of FIG. 5 , when the polarization components “a+b” and“a+be^(iπ)” are allocated to the reception channels, the signalcomponents)“S1(+45°) and S2(+45°)” and “S1(−45° and S2(−45°)” of thecomposed orthogonal polarization different from the orthogonalpolarization characteristics of the reception antenna element 1314 areoutput to the reception channels, with respect to the RF signals S1 andS1.

FIGS. 2A to 2D illustrate that the antenna apparatus 10 includes onetransmission polarization composition unit 1130 and one transmissionpolarization allocation unit 1140, which integratedly performpolarization composition and polarization allocation with respect to alltransmission signals or transmission channels.

However, in another embodiment, the antenna apparatus 10 may also beconfigured to include a plurality of transmission polarizationcomposition units and a plurality of transmission polarizationallocation units which perform the polarization composition and thepolarization allocation with respect to the transmission signals or thetransmission channels related to respective transmission beams.Similarly, the antenna apparatus 10 may also be configured to include aplurality of reception polarization composition units and a plurality ofreception polarization allocation units. An example of such aconfiguration is illustrated in FIG. 6 .

FIG. 6 is a block diagram illustrating an exemplary structure forperforming polarization composition and polarization allocation fortransmission signals in the antenna apparatus according to an embodimentof the present disclosure.

Referring to FIG. 6 , the antenna apparatus may be configured to includea plurality of polarization composition units 1130-1 to 1130-M, aplurality of polarization allocation units 1140-1 to 1140-M, and apolarization allocation control unit 1142. The polarization allocationcontrol unit 1142 integratedly manages the polarization allocation ofthe transmission signals performed by the plurality of transmissionpolarization composition units 1130-1 to 1130-M.

The polarization allocation control unit 1142 may determine theorthogonal polarizations for the respective transmission channels basedon the number of beams and an orthogonal polarization of a referencebeam. Here, the number of beams may mean the number of beams to begenerated by using the array antenna 130, and the reference beam may beany one beam (for example, a transmission beam related to a firsttransmission channel and a second transmission channel among Mtransmission channels) predefined among multiple beams. The polarizationallocation control unit 1142 may determine the orthogonal polarizationsfor the respective transmission channels so that transmission beamsneighboring to each other among multiple transmission beams havedifferent orthogonal polarizations.

The polarization allocation control unit 1142 may generate allocationcontrol signals for controlling allocation of the orthogonalpolarizations to the transmission channels. The polarization allocationcontrol unit 1142 may transmit the allocation control signals thepolarization allocation units 1140-1 to 1140-M. The respectivepolarization allocation units 1140-1 to 1140-M may output polarizationcomponents corresponding to the orthogonal polarizations indicated bythe allocation control signal among four polarization componentsgenerated by the corresponding polarization composition units 1130-1 to1130-M.

The polarization components output by the respective polarizationallocation units 1140-1 to 1140-M are supplied to correspondingtransmission antenna elements 1312 via subsequent components. Thetransmission signals to which the orthogonal polarizations are allocatedmay be radiated to beams of different orientations in the free spacethrough the transmission antenna elements 1312. The spatial polarizationseparation may be configured by at least one direction of the horizontaldirection and the vertical direction.

FIG. 7 is a conceptual view for describing spatial polarizationseparation in a horizontal direction and a vertical direction providedby the antenna apparatus according to an embodiment of the presentdisclosure.

As illustrated in FIG. 7 , the antenna apparatus 10 may form c beamsseparated in the horizontal direction to correspond to c sectors byusing the array antenna 130, and form d beams separated in the verticaldirection for each of c sectors. That is, the antenna apparatus 10 mayprovide 3D beamforming. The numbers of spatially separated beams in thevertical direction for respective sectors may also be the same as ordifferent from each other. Therefore, a coverage area of the antennaapparatus 10 may be divided into up to c x d subsectors.

With respect to the beams separated in the horizontal direction,contiguous beams have different orthogonal polarizations (that is,spatial polarization separation in the horizontal direction), and as aresult, a correlation between horizontally contiguous beams may besufficiently small. Further, in each sector, with respect to the beamsseparated in the vertical direction, the contiguous beams may havedifferent orthogonal polarizations (that is, the spatial polarizationseparation in the vertical direction), and a correlation betweenvertically contiguous beams may be sufficiently small. Furthermore,beams (for example, a first beam of a first sector and a second beam ofa second sector) having the same orthogonal polarization betweencontiguous sectors are sufficiently spaced in the horizontal directionand in the vertical direction, so a correlation between two beams mayalso be sufficiently small.

Previously, it is noted that the antenna apparatus using two kinds oforthogonal polarizations jointly is not attempted due to a highcorrelation between the ±45° orthogonal polarization and the H/Vorthogonal polarization. The antenna apparatus 10 according to thepresent disclosure allocates different orthogonal polarizations betweenspatially contiguous beams to improve the correlation between theorthogonal polarizations, thereby implementing polarization reusecapable of perfectly using efficiency of a polarization diversityprovided by two kinds of orthogonal polarizations (that is, fourdifferent polarizations). The term “polarization reuse” is based onfrequency reuse.

FIG. 8 is a conceptual view for describing temporal polarizationseparation provided by the antenna apparatus according to an embodimentof the present disclosure.

The antenna apparatus 10 according to the present disclosure allocatestwo kinds of orthogonal polarizations to the transmission channel andthe reception channel so that the transmission beam and the receptionbeam formed in the same direction have different orthogonalpolarizations to temporally separate two kinds of orthogonalpolarizations.

In FIG. 8 , an area Tx marked with a hatched line represents a timeinterval in which the signal is transmitted through the transmissionantenna element 1312, and an area Rx not marked with the hatched linerepresents a time interval in which the signal is received through thereception antenna element 1314.

In the example of FIG. 8 , the orthogonal polarization is used during atransmission time interval, and the vertical/horizontal orthogonalpolarization is used during a reception time interval, so differentorthogonal polarizations are temporally separated and used. Contrary tothe example, it should be appreciated that the ±45° orthogonalpolarization may be used during the reception time interval, and thevertical/horizontal orthogonal polarization is used during thetransmission time interval.

In particular, in the antenna apparatus 10 according to the presentdisclosure, orthogonal polarization characteristics of the transmissionantenna element and the reception antenna element used for a TDDoperation may also be different from each other, and as a result,orthogonal polarizations used for transmission of the signal andreception of the signal may be different from each other.

Channel Non-Reciprocity Correction

Channel reciprocity is a premise that channel characteristics of adownlink channel and an uplink channel are the same as each other in thesame frequency band. That is, the channel reciprocity means a propertythat the downlink channel and the uplink channel have similarcharacteristics to each other.

When the channel reciprocity is used, it is possible to for the basestation to estimate a downlink channel response by using an uplinkchannel response or estimate the uplink channel response by using thedownlink channel response. Therefore, the channel reciprocity may be alargest advantage which a time division duplexing (TDD) scheme ascompared with a frequency division duplexing (FDD) scheme.

FIG. 9 is a conceptual view for describing a channel non-reciprocityproblem which may occur when the antenna apparatus uses different dualpolarized waves between transmission of a signal and reception of thesignal.

As described above, the antenna apparatus according to the presentdisclosure uses the spatial polarization separation and the temporalpolarization separation. Therefore, the orthogonal polarization of thetransmission beam formed in a certain spatial direction may be differentfrom the orthogonal polarization characteristics of the receptionantenna element used for receiving the radio signal from the certainspatial direction. For example, in a certain spatial direction, thetransmission beam may have the ±45° orthogonal polarization and thereception antenna element may have the H/V orthogonal polarizationcharacteristics. As another example, the transmission beam may have theH/V orthogonal polarization, and the reception antenna element may havethe ±45° orthogonal polarization characteristics. As such, whendifferent orthogonal polarizations are used in the downlink and theuplink, the radio channel characteristics between the uplink and thedownlink are different, and as a result, the channel reciprocity betweenthe downlink and the uplink is not established. That is, the channelnon-reciprocity occurs.

Non-establishment of the channel reciprocity (that is, the occurrence ofthe channel non-reciprocity) is not an issue when the beamforming is notperformed or when beamforming based on a channel stateinformation-reference signal (CSI-RS), which the gNB transmits to the UEin 5G NR, is performed. However, when beamforming based on a soundingreference signal (SRS) is performed, the non-establishment of channelreciprocity may deteriorate the performance of the antenna apparatus.

The SRS is an uplink reference signal which the UE transmits the gNB toestimate the state of the uplink channel, and the UE aperiodicallytransmits the SRS to the gNB to announce state information of the uplinkchannel. The gNB may estimate channel state information (CSI) of theuplink channel based on the received SRS, and determine downlinkbeamforming based on the estimated CSI.

Therefore, if the channel reciprocity is not established, theperformance of the antenna apparatus may be deteriorated when the weightvector acquired based on the SRS is used in the downlink teamforming.

In order to solve the problem, the antenna apparatus according to theembodiments of the present disclosure matches the orthogonalpolarization of the reception signals with the orthogonal polarizationof the transmission channels (or transmission beam) through signalprocessing of the reception signals to correct the channelnon-reciprocity (that is, acquire or retain the channel reciprocity).

As described above, the correction of the channel non-reciprocity may beachieved by the polarization conversion of the polarization conversionunit 1160, alternatively, by the polarization composition and thepolarization allocation of the polarization composition unit 1170 andthe polarization allocation unit 1180. Hereinafter, exemplary structuresfor correcting the channel non-reciprocity and an operation thereof willbe described with reference to FIG. 10A, FIG. 10B, FIG. 11A and FIG.11B.

The exemplary structure of FIGS. 10A and 10B includes the polarizationconversion unit 1160 which is configured to perfom the function ofcorrecting the channel non-reciprocity.

In the example of FIG. 10A, the orthogonal polarization characteristics(V/H) of the reception antenna element 1314 are different from theorthogonal polarization)(±45° of the radio wave (or transmission beam)of the downlink channel, so the channel non-reciprocity correction isrequired.

Referring to FIG. 10A, two digital transmission signals to which the±45° orthogonal polarization is allocated are subjected to the RF signalprocessing of the RF chain 1210 and fed to the transmission antennaelement 1312. When the polarization components corresponding to the ±45°orthogonal polarization are input into the transmission RF chain, thetransmission antenna element 1312 has the ±45° orthogonal polarizationcharacteristics, so the radio wave of the downlink channel has the ±45°orthogonal polarization. The reception antenna element 1314 receives theradio wave of the uplink channel and outputs an analog reception signal.The reception antenna element 1314 has the V/H orthogonal polarizationcharacteristics, so the analog reception signal corresponds to the V/Horthogonal polarization component of the radio wave. The analogreception signals are subjected to the RF signal processing of thereception RF chain 1220, and converted into digital reception signals.

The polarization conversion unit 1160 performs the polarizationconversion for the digital reception signals to output polarizationconverted signals having the same orthogonal polarization as theorthogonal polarization of the downlink channel. The polarizationconversion performed by the polarization conversion unit 1160 may beimplemented through the matrix operation of Equation 2 below.

$\begin{matrix}{{\begin{pmatrix}1 & 1 \\1 & e^{j\pi}\end{pmatrix}\begin{pmatrix}a \\b\end{pmatrix}} = \begin{pmatrix}{a + b} \\{a + {be}^{j\pi}}\end{pmatrix}} & \left\lbrack {{Equation}2} \right\rbrack\end{matrix}$

In Equation 2, a and b are the digital reception signals input into thepolarization conversion unit 1160, and a+b and a+b& are the polarizationconverted reception signals output from the polarization conversion unit1160. Furthermore,

$\begin{pmatrix}1 & 1 \\1 & e^{j\pi}\end{pmatrix}$

represents a polarization decomposition (PD) matrix for the conversionof the orthogonal polarization. However, in order to avoid the power ofthe polarization converted reception signal from being increased, thescale coefficient may be applied to all elements in the PD matrix. Thescale coefficient may be 1/√2.

In the example of FIG. 10B, since the orthogonal polarizationcharacteristics (V/H) of the reception antenna element 1314 coincidewith the orthogonal polarization (V/H) of the radio wave (ortransmission beam) of the downlink channel, the channel non-reciprocitycorrection is not required. Therefore, the polarization conversion unit1160 outputs the input digital reception signals as they are without thepolarization conversion.

In the exemplary structures of FIGS. 11A and 11B, the function ofcorrecting the channel non-reciprocity is implemented by thepolarization allocation control unit 1142, the reception polarizationcomposition unit 1170, and the reception polarization allocation unit1180.

In the example of FIG. 11A, since the orthogonal polarizationcharacteristics (V/H) of the reception antenna element 1314 aredifferent from the orthogonal polarization)(±45° of the radio wave (ortransmission beam) of the downlink channel, the channel non-reciprocitycorrection is required. Therefore, the orthogonal polarization of thesignals input into the reception polarization composition unit 1170 isdifferent from those of the signal output from the receptionpolarization allocation unit 1180.

Referring to FIG. 11A, the reception polarization composition unit 1170generates four polarization components for a pair of transmissionsignals, and the reception polarization allocation unit 1140 outputs twopolarization components corresponding to the ±45° orthogonalpolarization in response to the control signal of the polarizationallocation control unit 1142. The two polarization components are fed tothe transmission antenna element 1312 via the transmission RF chain1210. The transmission antenna element 1312 has the ±45° orthogonalpolarization characteristics, so the radio wave (or transmission beam)of the downlink channel has the ±45° orthogonal polarization.

The reception antenna element 1314 receives the radio wave of the uplinkchannel and outputs two analog reception signals. The reception antennaelement 1314 has the V/H orthogonal polarization characteristics, so twoanalog reception signals correspond to the V/H orthogonal polarizationcomponent of the radio wave. The two analog reception signals aresubjected to the RF signal processing of the reception RF chain 1220,and converted into two digital reception signals. The receptionpolarization composition unit 1170 may compose four orthogonalpolarization components from the two digital reception signals.

In order to correct the channel non-reciprocity, the polarizationallocation control unit 1142 selects the same orthogonal polarization(i.e., ±45° orthogonal polarization) as the orthogonal polarizationselected for the transmission polarization allocation unit 1140, andtransmits an allocation control signal indicating the selectedorthogonal polarization to the reception polarization allocation unit1180. The reception polarization allocation unit 1180 outputs twopolarization components corresponding to the orthogonal polarization(i.e., ±45° orthogonal polarization) indicated by the allocation controlsignal among the four orthogonal polarization components.

In the example of FIG. 11B, since the orthogonal polarizationcharacteristics (V/H) of the reception antenna element 1314 coincidewith the orthogonal polarization (V/H) of the radio wave (ortransmission beam) of the downlink channel, the channel non-reciprocitycorrection is not required. Therefore, the orthogonal polarization ofthe signals input into the reception polarization composition unit 1170is not different from those of the signals output from the receptionpolarization allocation unit 1314.

Referring to FIG. 11B, the reception polarization allocation unit 1140outputs two polarization components corresponding to the V/H orthogonalpolarization in response to the control signal of the polarizationallocation control unit 1142. The polarization components are fed to thetransmission antenna element 1312 via the transmission RF chain 1210.The transmission antenna element 1312 has the ±45° orthogonalpolarization characteristics, so the radio wave (or transmission beam)of the downlink channel has the V/H orthogonal polarization by thepolarization composition.

The reception antenna element 1314 receives the radio wave of the uplinkchannel and outputs two analog reception signals. The reception antennaelement 1314 has the V/H orthogonal polarization characteristics, so twoanalog reception signals correspond to the V/H orthogonal polarizationcomponent of the radio wave. Two analog reception signals are subjectedto the RF signal processing of the reception RF chain 1220, andconverted into two digital reception signals. The reception polarizationcomposition unit 1170 may compose four orthogonal polarizationcomponents from two digital reception signals.

The polarization allocation control unit 1142 selects the sameorthogonal polarization (i.e., V/H orthogonal polarization) as theorthogonal polarization selected for the transmission polarizationallocation unit 1140, and transmits an allocation control signalindicating the selected orthogonal polarization to the receptionpolarization allocation unit 1180. The reception polarization allocationunit 1180 outputs two polarization components corresponding to theorthogonal polarization (i.e., V/H orthogonal polarization) indicated bythe allocation control signal among the four orthogonal polarizationcomponents.

As such, the antenna apparatus 10 according to the present disclosureperforms the polarization conversion or performs the polarizationcomposition and the polarization allocation, for the reception signalsinput from the reception antenna element 1314, and thereby can outputsignal components corresponding to the same orthogonal polarization asthe orthogonal polarization of the downlink channel (or of thetransmission beam or the transmission channels). As a result, thenon-reciprocity between the uplink channel and the downlink channel canbe corrected, and the deterioration of the performance of thetransmission beamforming performed based on uplink channel stateinformation (CSI) estimated from the SRS received via the uplink channelmay be presented. Moreover, since the channel non-reciprocity iscorrected through the signal processing for the reception signals in theantenna apparatus 10, the channel reciprocity may be secured or retainedin the DU.

Amplitude-Phase Calibration

As mentioned above, in FIGS. 2A and 2B, the amplitude-phase calibrationunit 1150 may calibrate variations of an amplitude change and a phasechange of the polarization occurred while the RF signals moves throughRF paths.

The amplitude-phase calibration unit 1150 may be implemented as onecomponent which integratedly performs amplitude and phase calibrationfor a plurality of transmission/reception signals ortransmission/reception channels, and alternatively, also constituted bya plurality of modules which individually perform the amplitude andphase calibration for each of the plurality of transmission/receptionsignals or transmission/reception channels.

Since accuracy of the polarization composition which occurs in theantenna array 130 according to the present disclosure significantlydepends on the amplitudes and phases of the composed radio signals, thecalibration of the amplitude and the phase increases the accuracy of thepolarization composition. Therefore, the amplitude and phase calibrationmay also be applied to all RF paths, but may also be selectively appliedonly to transmission paths requiring the polarization composition amonga plurality of RF transmission paths and reception paths requiring thechannel non-reciprocity correction among a plurality of RF receptionpaths.

FIG. 12 is a block diagram illustrating an exemplary structure forperforming transmission polarization composition calibration in theantenna apparatus according to an embodiment of the present disclosure.

As illustrated in FIG. 12 , the amplitude-phase calibration unit 1150may be configured to include a calibration control unit 1152 and aplurality of calibration execution units 1154.

The correction control unit 1152 integratedly manages the amplitude andphase calibration performed with respect to a plurality of transmissionchannels. The calibration control unit 1152 compares the “polarizationcomponents output from the transmission polarization allocation unit1140” and the “polarization components output from the transmission RFchain 1210” to generate a calibration control signal for controlling theamplitude and phase calibration to be performed by the calibrationexecution unit 1154. The calibration control signal may include anamplitude value and a phase value to be calibrated.

The calibration control unit 1152 may transmit a respective calibrationcontrol signal to each calibration execution unit 1154. Each calibrationexecution unit 1154 may calibrate the amplitude and the phase based onthe respective calibration control signal.

As described above, among a plurality of transmission paths, theamplitude and phase calibration may also be selectively applied only totransmission paths in which the orthogonal polarization allocated to thetransmission path is different from the orthogonal polarizationcharacteristics of the transmission antenna element (therefore, thepolarization composition occurs in the transmission antenna element).

Therefore, when the polarization composition does not occur in thetransmission antenna element, the calibration control unit 1152 may nottransmit the calibration control signal to the related calibrationexecution unit 1154 or may transmit a calibration control signal inwhich each of an amplitude value and a phase value to be calibrated isset to 0 (zero) to the related calibration execution unit 1154.

Referring to FIG. 12 , since the polarization allocation unit 1140-1outputs the polarization components “a” and “b” to two transmissionchannels, respectively, a transmission beam radiated from the relatedtransmission antenna element 1312 does not involve the polarizationcomposition. Therefore, the calibration control unit 1152 may nottransmit the calibration control signal to the calibration executionunit 1154-1 or may transmit a calibration control signal in which eachof an amplitude value and a phase value to be calibrated is set to 0(zero) to the calibration execution unit 1154-1. On the contrary, sincethe polarization allocation unit 1140-E outputs polarization components“i+j” and “i+je^(iπ)” to two transmission channels, respectively, thetransmission beam radiated from the related transmission antenna element1312 involves the polarization composition. Therefore, the calibrationcontrol unit 1152 compares the polarization components output from thetransmission polarization allocation unit 1140-E and the polarizationcomponents output from transmission RF chains 1210 E-1 and 1210 E-2 tocalculate a variation between the transmission RF chains 1210 E-1 and1210 E-2, and generate the calibration control signal for controllingthe amplitude and phase calibration to be performed by the calibrationexecution unit 1154-E. The calibration execution unit 1154-E adjustsamplitudes and phases of the polarization components from thetransmission polarization allocation unit 1140-E based on thecalibration control signal to compensate for variations of amplitude andphase characteristics of the RF path between the transmission RF chain1210 E-1 and the transmission RF chain 1210 E-2.

The structure illustrated in FIG. 12 and an operation method thereof maybe equally applied even to compensating for the variations of theamplitude and phase characteristics of the RF path between the receptionRF chains 1210-1 to 1210-M.

Through the amplitude-phase calibration function, the polarizationcomposition which occurs in the antenna array 130 and the channelnon-reciprocity correction may be more accurately achieved. Further, theamplitude-phase calibration function is selectively applied only to thetransmission paths involving the polarization composition and thereception paths involving the channel non-reciprocity correction toreduce an operation burden according to the generation of thecalibration control signal of the calibration control unit 1152, whichenables quick amplitude-phase calibration.

FIG. 13 is a flowchart illustrating a method performed by a multi-beamantenna apparatus using quadruple polarization according to anembodiment of the present disclosure. The multi-beam antenna apparatusincludes an array antenna which includes transmission antenna elementsused for forming a plurality of transmission beams and reception antennaelements used for forming a plurality of reception beams.

The multi-beam antenna apparatus may generate a plurality oftransmission polarization components from transmission signalscorresponding to a pair of transmission channels related to eachtransmission beam (S1310).

The multi-beam antenna apparatus may output a pair of transmissionpolarization components corresponding to a first orthogonal polarizationor a pair of transmission polarization components corresponding to asecond orthogonal polarization among the plurality of transmissionpolarization components with respect to a pair of transmission channelsrelated to each transmission beam so that spatially contiguoustransmission beams have different orthogonal polarizations (S1320).

When a pair of transmission polarization components corresponding to thefirst orthogonal polarization are radiated to the transmission antennaelements having the first orthogonal polarization, the transmission beamhaving the first orthogonal polarization may be formed (that is, thepolarization composition does not occur). When a pair of receptionpolarization components corresponding to the second orthogonalpolarization are radiated to the transmission antenna elements havingthe first orthogonal polarization, the transmission beam having thesecond orthogonal polarization may be formed by the polarizationcomposition.

The multi-beam antenna apparatus may adjust the amplitudes and thephases of the one pair of transmission polarization components in orderto calibrate the variations of the amplitudes and the phasecharacteristics between the one pair of transmission paths correspondingto one pair of transmission channels related to each transmission beam(S1330).

The calibration of the variations of the amplitude and phasecharacteristics between the transmission paths may be performed onlywhen the transmission beam has a different orthogonal polarization fromthe orthogonal polarization characteristics of the transmission antennaelements by the polarization composition. That is, when an orthogonalpolarization of a given transmission beam is different from theorthogonal polarization characteristics of the related transmissionantenna elements, the multi-beam antenna apparatus may adjust theamplitudes and the phases of a pair of transmission polarizationcomponents in order to calibrate the variations of the amplitude andphase characteristics between a pair of transmission paths related tothe given transmission beam. Further, when the orthogonal polarizationof the given transmission beam is the same as the orthogonalpolarization characteristics of the related transmission antennaelements, the multi-beam antenna apparatus may not calibrate thevariations of the amplitude and phase characteristics between a pair oftransmission paths related to the given transmission beam.

The multi-beam antenna apparatus may adjust amplitudes and phases of apair of reception signals output from a pair of reception paths in orderto calibrate the variations of the amplitude and phase characteristicsbetween a pair of reception paths corresponding to a pair of receptionchannels related to each reception beam (S1340).

Calibrating the variations of the amplitude and phase characteristicsbetween the reception paths may be performed only for a pair ofreception signals input from the reception antenna element havingdifferent orthogonal polarization characteristics from the correspondingtransmission beam (as a result, the channel non-reciprocity calibrationis required). Therefore, when orthogonal polarization characteristics ofthe reception antenna elements related to the given reception beam aredifferent from the orthogonal polarization of the transmission beamformed in the spatially same direction, the multi-beam antenna apparatusmay adjust the amplitudes and the phases of a pair of reception signalsrelated to the given reception beam in order to calibrate the variationsof the amplitude and phase characteristics between a pair of receptionrelated to the given reception beam. Further, when the orthogonalpolarization characteristics of the reception antenna elements relatedto the given reception beam are the same as the orthogonal polarizationof the transmission beam formed in the spatially same direction, themulti-beam antenna apparatus may not calibrate the variations of theamplitude and phase characteristics between a pair of reception pathsrelated to the given reception beam.

The multi-beam antenna apparatus may perform channel non-reciprocitycorrection for the reception signals corresponding to a pair ofreception channels related to each reception beam (S1350).

In some embodiments, as a part of performing the channel non-reciprocitycorrection (S1350), the multi-beam antenna apparatus may generatepolarization-converted signals corresponding to the orthogonalpolarization of the transmission beam formed in the spatially samedirection as each reception beam from the reception signalscorresponding to a pair of reception channels related to each receptionbeam. Specifically, the multi-beam antenna apparatus performs thepolarization conversion for a pair of reception signals input from thereception antenna element having the different orthogonal polarizationcharacteristics from the orthogonal polarization of the correspondingtransmission beam (as a result, the channel non-reciprocity correctionis required) to output a pair of reception polarization componentscorresponding to the orthogonal polarization of the transmission beamformed in the spatially same direction.

In some other embodiments, as a part of performing the channelnon-reciprocity correction (S1350), the multi-beam antenna apparatus maygenerate a plurality of reception polarization components from thereception signals corresponding to a pair of reception channels relatedto each reception beam. Further, the multi-beam antenna apparatus mayoutput a pair of reception polarization components corresponding to theorthogonal polarization of the transmission beam formed in the spatiallysame direction among the plurality of reception polarization componentswith respect to a pair of reception channels related to each receptionbeam.

Although exemplary embodiments of the present disclosure have beendescribed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions, and substitutions arepossible, without departing from the idea and scope of the claimedinvention. Therefore, exemplary embodiments of the present disclosurehave been described for the sake of brevity and clarity. The scope ofthe technical idea of the present embodiments is not limited by theillustrations. Accordingly, one of ordinary skill would understand thatthe scope of the claimed invention is not to be limited by the aboveexplicitly described embodiments but by the claims and equivalentsthereof

What is claimed is:
 1. A method performed by a multi-beam antennaapparatus using two kinds of orthogonal polarizations, wherein themulti-beam antenna apparatus includes an array antenna includingtransmission antenna elements used to form a plurality of transmissionbeams and reception antenna elements used to form a plurality ofreception beams, the method comprising: generating a plurality oftransmission polarization components from transmission signalscorresponding to a pair of transmission channels related to eachtransmission beam; outputting a pair of transmission polarizationcomponents corresponding to a first orthogonal polarization or a pair oftransmission polarization components corresponding to a secondorthogonal polarization among the plurality of transmission polarizationcomponents with respect to a pair of transmission channels related toeach transmission beam so that spatially contiguous transmission beamshave different orthogonal polarizations; and generatingpolarization-converted signals corresponding to an orthogonalpolarization of a transmission beam formed in the spatially samedirection as each reception beam from reception signals corresponding toa pair of reception channels related to each reception beam.
 2. Themethod of claim 1, wherein when a pair of transmission polarizationcomponents corresponding to the first orthogonal polarization areradiated to the transmission antenna elements having the firstorthogonal polarization, the transmission beam having the firstorthogonal polarization is formed, and when a pair of transmissionpolarization components corresponding to the second orthogonalpolarization are radiated to the transmission antenna elements havingthe first orthogonal polarization, the transmission beam having thesecond orthogonal polarization by polarization composition is formed. 3.The method of claim 1, further comprising: adjusting amplitudes andphases of the one pair of transmission polarization components in orderto calibrate variations of amplitude and phase characteristics betweenone pair of transmission paths related to each transmission beam.
 4. Themethod of claim 1, further comprising: adjusting, when an orthogonalpolarization of a given transmission beam is different from theorthogonal polarization characteristics of the related transmissionantenna elements, the amplitudes and the phases of a pair oftransmission polarization components in order to calibrate thevariations of the amplitude and phase characteristics between a pair oftransmission paths related to the given transmission beam.
 5. The methodof claim 1, further comprising: adjusting amplitudes and phases of theone pair of reception polarization components in order to calibratevariations of amplitude and phase characteristics between one pair ofreception paths related to each reception beam.
 6. The method of claim1, further comprising: adjusting, when orthogonal polarizationcharacteristics of the reception antenna elements related to the givenreception beam are different from the orthogonal polarization of thetransmission beam formed in the spatially same direction, the amplitudesand the phases of a pair of reception signals related to the givenreception beam in order to calibrate the variations of the amplitude andphase characteristics between a pair of reception related to the givenreception beam.
 7. The method of claim 1, wherein the transmissionantenna elements have different orthogonal polarization characteristicsfrom those of the reception antenna elements.
 8. The method of claim 1,wherein the transmission antenna elements have the same orthogonalpolarization characteristics as those of the reception antenna elements.9. A multi-beam antenna apparatus using two kinds of orthogonalpolarizations, the apparatus comprising: an array antenna includingtransmission antenna elements used for forming a plurality oftransmission beams and reception antenna elements used for forming aplurality of reception beams; a transmission polarization compositionunit for generating a plurality of transmission polarization componentsfrom transmission signals corresponding to a pair of transmissionchannels related to each transmission beam; a transmission polarizationallocation unit for outputting a pair of transmission polarizationcomponents corresponding to a first orthogonal polarization or a pair oftransmission polarization components corresponding to a secondorthogonal polarization among the plurality of transmission polarizationcomponents with respect to a pair of transmission channels related toeach transmission beam so that spatially contiguous transmission beamshave different orthogonal polarizations; and a polarization conversionunit for generating polarization-converted signals corresponding to anorthogonal polarization of a transmission beam formed in the spatiallysame direction as each reception beam from reception signalscorresponding to a pair of reception channels related to each receptionbeam.
 10. The multi-beam antenna apparatus of claim 9, wherein when apair of transmission polarization components corresponding to the firstorthogonal polarization are radiated to the transmission antennaelements having the first orthogonal polarization, the transmission beamhaving the first orthogonal polarization is formed, and when a pair oftransmission polarization components corresponding to the secondorthogonal polarization are radiated to the transmission antennaelements having the first orthogonal polarization, the transmission beamhaving the second orthogonal polarization by polarization composition isformed.
 11. The multi-beam antenna apparatus of claim 9, furthercomprising: a plurality of transmission RF chains forming a plurality oftransmission paths corresponding to the plurality of transmissionchannels and a plurality of reception RF chains forming a plurality ofreception paths corresponding to the plurality of reception channels;and an amplitude-phase calibration unit for adjusting amplitudes andphases of the one pair of transmission polarization components in orderto variations of amplitude and phase characteristics between one pair oftransmission paths related to each transmission beam, and adjusting theamplitudes and the phases for the one pair of reception signals in orderto calibrate variations of amplitude and phase characteristics betweenone pair of reception paths related to each reception beam.
 12. Themulti-beam antenna apparatus of claim 11, wherein the amplitude-phasecalibration unit is configured to adjust, when an orthogonalpolarization of a given transmission beam is different from theorthogonal polarization characteristics of the related transmissionantenna elements, the amplitudes and the phases of a pair oftransmission polarization components in order to calibrate thevariations of the amplitude and phase characteristics between a pair oftransmission paths related to the given transmission beam.
 13. Themulti-beam antenna apparatus of claim 11, wherein the amplitude-phasecalibration unit is configured to adjust, when orthogonal polarizationcharacteristics of the reception antenna elements related to the givenreception beam are different from the orthogonal polarization of thetransmission beam formed in the spatially same direction, the amplitudesand the phases of a pair of reception signals related to the givenreception beam in order to calibrate the variations of the amplitude andphase characteristics between a pair of reception related to the givenreception beam.
 14. The multi-beam antenna apparatus of claim 9, whereinthe transmission antenna elements have different orthogonal polarizationcharacteristics from those of the reception antenna elements.
 15. Themulti-beam antenna apparatus of claim 9, wherein the transmissionantenna elements have the same orthogonal polarization characteristicsas those of the reception antenna elements.